Abstract

Recent progress in high power, slab waveguide CO₂ lasers, using RF excitation, has achieved specific power output approaching 30 kW·m^-2 and absolute laser output powers in the kilowatt regime. These devices commonly employ a hybrid unstable resonator, or a plane mirror waveguide resonator containing a partially reflecting output coupler. Unstable resonators have the advantage of all-reflective mirrors and edge coupling, but are unable to provide sufficient frequency purity and beam quality for some applications, such as lidar and remote sensing. For large aperture devices using stable cavities, partially transmitting output mirrors, usually of ZnSe become expensive and are more readily damaged than full reflectors, whilst the large output beam provides difficulty with the subsequent beam handling. There is thus a need for a new resonator approach, which can deliver a small aperture beam from wide slab lasers, with good beam quality and spectral purity, using all-reflective optics.

© 1994 IEEE